scholarly journals Influence of Scanning Strategy on the Performances of GO-Reinforced Ti6Al4V Nanocomposites Manufactured by SLM

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1379
Author(s):  
Xiaojin Miao ◽  
Xin Liu ◽  
Peipei Lu ◽  
Jitai Han ◽  
Weipeng Duan ◽  
...  
Keyword(s):  
Temperature Gradients ◽  
Experimental Results ◽  
Laser Melting ◽  
Scanning Strategy ◽  
Concentration Effects ◽  
Powder Bed ◽  
Simulation Results ◽  
Scanning Strategies ◽  
Matrix Nanocomposites ◽  
Simulation Scheme

In this work, the effects of line (L-scanning strategy), stripe (S-scanning strategy), hollow square (H-scanning strategy) and chess board partition (C-scanning strategy) on the performances of graphene oxide reinforced Ti6Al4V matrix nanocomposites (GO/TC4) as fabricated by selective laser melting (SLM) were investigated. Numerical temperature field simulation of four different scanning strategies was utilized to investigate the effects of thermal concentration on SLM-processed GO/TC4 nanocomposites, linking to its micro-voids, surface roughness, porosity, microhardness and tribological properties. The proposed simulation scheme is validated by comparing the simulated thermal analysis with experimental results. Simulation results show that the thermal concentration effects of a part during SLM process is distinctive under different scanning strategies, with the slowest cooling rate of 64,977.5 °C/s that is achieved by C-scanning strategy specimen. The experimental results indicate that the performances of the L-scanning strategy or S-scanning strategy sample are seriously affected by the thermal concentration, causing a large number of micro-voids and defects. All the experimental results suggest that the sample using C-scanning strategy exhibits the optimal performance of all investigated specimens, which closely correlates with its lowest temperature gradients. This study highlights the importance of using a partition scanning strategy during SLM process, which can be easily extended to other powder bed fusion process.

scholarly journals Study on laser powder bed fusion of nickel-base alloy of G-surface structure: scanning strategy, properties and compression properties

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bo Qian ◽  
Hongri Fan ◽  
Jianrui Zhang ◽  
Tengfei Li ◽  
Jiangtao Xi ◽  
...  
Keyword(s):  
Surface Structure ◽  
Base Alloy ◽  
Nickel Base Alloy ◽  
Laser Powder Bed Fusion ◽  
Scanning Strategy ◽  
Powder Bed ◽  
Compression Performance ◽  
Solid Structure ◽  
Nickel Base ◽  
Scanning Strategies

AbstractAiming at laser powder bed fusion of GH3536 nickel base alloy, the effects of different scanning strategies on microstructure, porosity and mechanical properties were explored. In the aspect of microstructure and micro hardness of the sample, three scanning strategies had little difference; in the aspect of macro mechanical properties of the sample, the slope subarea scanning was better than the helix and island scanning. On this basis, the slope subarea scanning was selected as the optimal scanning strategy to form the G-surface structure, and the compression performance of G-surface was studied. The results showed that: (1) the compression performance of G-surface structure was smaller than that of solid structure, The compression strength of G-surface can only reach about 20% of solid structure: the average strength value of G-surface is 220 MPa, solid structure is 1.1 GMpa; while G-surface structure had a smooth compression curve, which indicated the good energy absorption characteristics; (2) with the increase of wall thickness, the mechanical performance of G-surface structure was also enhanced, while the energy absorption capacity was constantly reduced; (3) with the same wall thickness, the compression performance of sample in building direction (BD) is higher than that in horizontal direction (HD).

scholarly journals The Effect of a Scanning Strategy on the Residual Stress of 316L Steel Parts Fabricated by Selective Laser Melting (SLM)

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1821 ◽  
Author(s):  
Di Wang ◽  
Shibiao Wu ◽  
Yongqiang Yang ◽  
Wenhao Dou ◽  
Shishi Deng ◽  
...  
Keyword(s):  
Residual Stress ◽  
Selective Laser Melting ◽  
Laser Scanning ◽  
Effective Means ◽  
Laser Melting ◽  
Scanning Strategy ◽  
Deformation Degree ◽  
316L Steel ◽  
Stress And Deformation ◽  
Scanning Strategies

The laser scanning strategy has an important influence on the surface quality, residual stress, and deformation of the molten metal (deformation behavior). A divisional scanning strategy is an effective means used to reduce the internal stress of the selective laser melting (SLM) metal part. In order to understand and optimize the divisional scanning strategy, three divisional scanning strategies and an S-shaped orthogonal scanning strategy are used to produce 316L steel parts in this study. The influence of scanning strategy on the produced parts is verified from the aspects of densification, residual stress distribution and deformation. Experiments show that the 316L steel alloy parts adopted spiral divisional scanning strategy can not only obtain the densification of 99.37%, but they also effectively improve the distribution of residual stress and control the deformation degree of the produced parts. Among them, the spiral divisional scanning sample has the smallest residual stress in plane direction, and its σx and σy stress are controlled within 204 MPa and 103 MPa. The above results show that the spiral divisional scanning is the most conducive strategy to obtain higher residual stress performance of SLM 316L steel parts.

scholarly journals Study on Laser Powder Bed Fusion of Nickel-base Alloy: Scanning Strategy, Properties and Compression Properties

2020 ◽  
Author(s):  
Bo Qian ◽  
Hongri Fan ◽  
Tengfei Li ◽  
Jianrui Zhang ◽  
Jiangtao Xi ◽  
...  
Keyword(s):  
Surface Structure ◽  
Base Alloy ◽  
Powder Bed Fusion ◽  
Nickel Base Alloy ◽  
Laser Powder Bed Fusion ◽  
Scanning Strategy ◽  
Powder Bed ◽  
Compression Performance ◽  
Nickel Base ◽  
Scanning Strategies

Abstract Aiming at laser powder bed fusion of GH3536 nickel base alloy, the effects of different scanning strategies on microstructure, porosity and mechanical properties were explored. In the aspect of microstructure and micro hardness of the sample, three scanning strategies had little difference; in the aspect of macro mechanical properties of the sample, the slope subarea scanning was better than the helix and island scanning. On this basis, the slope subarea scanning was selected as the optimal scanning strategy to form the G-surface structure, and the compression performance of G-surface was studied. The results showed that: (1) the compression performance of G-surface structure was smaller than that of solid structure; while G-surface structure had a smooth compression curve, which indicated the good energy absorption characteristics; (2) with the increase of wall thickness, the mechanical performance of G-surface structure was also enhanced, while the energy absorption capacity was constantly reduced; (3) with the same wall thickness, the compression performance of sample in building direction (BD) is higher than that in horizontal direction (HD).

scholarly journals Scanning Strategies in the PBF Process: A Critical Review

2020 ◽  
Author(s):  
Ehsan Malekipour ◽  
Hazim El-Mounayri
Keyword(s):  
Residual Stress ◽  
Critical Review ◽  
Heat Accumulation ◽  
Scanning Strategy ◽  
Homogeneous Microstructure ◽  
Powder Bed ◽  
Pros And Cons ◽  
Scanning Strategies ◽  
Metallic Parts ◽  
Powder Fusion

Abstract The powder-bed fusion (PBF) process is capable of producing near-fully dense metallic parts; however, various defects — particularly thermal abnormalities — can still be observed during the process. Some of these thermal defects — cracks, distortion, delamination of layers, and microporosity — cannot be removed by post-processing operations. The majority of these abnormalities are the result of residual stress, heat accumulation, lack of inter-track /inter-layer bonding, lack of powder fusion, or a combination of these factors. Modifying the scanning strategy (the topology of scanning tracks) can efficiently mitigate these abnormalities by adjusting the process parameters and adopting proper scanning patterns. The implementation of different scanning strategies significantly changes the ultimate quality of printed parts and manufacturing process lead time. Choosing a proper scanning strategy minimizes the residual stress and internal porosity, generates homogeneous microstructure, and avoids heat accumulation throughout the part during the printing process. In this work, we conducted a critical review of different scanning strategies, their pros and cons, limitations, and influence on the resulting properties of fabricated parts. Furthermore, we report the latest efforts for improvement of the current scanning strategies and introduce the-state-of-the-art strategies in the multi-laser PBF (ML-PBF) process. The insights provided here can assist scholars in evaluating existing scanning strategies and scanning patterns, and in identifying ways both to overcome scanning limitations and to modify them. On the other hand, it can assist manufacturers in selecting the best scanning strategies for their products based on their designs, demands, and resources.

scholarly journals A Study on the Dimension Accuracy on the Inner Structure of the 3D Printed Parts Caused by the Scanning Strategy

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1333
Author(s):  
Jitai Han ◽  
Meiping Wu ◽  
Yanan Ge
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Measured Data ◽  
Laser Melting ◽  
Scanning Strategy ◽  
Element Analysis ◽  
Dimensional Deviation ◽  
3D Printed ◽  
Scanning Strategies ◽  
Better Than

Selective laser melting (SLM) has been used in many fields recently, especially in the aerospace field. Many studies have been done on mechanical properties of the printed parts, but the dimension accuracy of the inner structure received little attention during these years. In this work, the dimension accuracy of the inner structure was measured and compared using different scanning strategies. Compared with the measured data, a new scanning strategy was used and finds that the dimension accuracy was better than the previous one that used a two-scanning strategy. To explain this phenomenon, finite element analysis (FEA) was used to show the temperature distribution after a 0.1 s cooling using two different scanning strategies, which caused the dimensional deviation in printing.

scholarly journals Microstructural and Tensile Properties Anisotropy of Selective Laser Melting Manufactured IN 625

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4829
Author(s):  
Mihaela Raluca Condruz ◽  
Gheorghe Matache ◽  
Alexandru Paraschiv ◽  
Tiberius Florian Frigioescu ◽  
Teodor Badea
Keyword(s):  
Tensile Properties ◽  
Selective Laser Melting ◽  
Experimental Investigations ◽  
Vertical Position ◽  
Laser Melting ◽  
Scanning Strategy ◽  
Specimen Orientation ◽  
Mechanical Performances ◽  
Scanning Strategies ◽  
Microstructural Anisotropy

The present study was focused on the assessment of microstructural anisotropy of IN 625 manufactured by selective laser melting (SLM) and its influence on the material’s room temperature tensile properties. Microstructural anisotropy was assessed based on computational and experimental investigations. Tensile specimens were manufactured using four building orientations (along Z, X, Y-axis, and tilted at 45° in the XZ plane) and three different scanning strategies (90°, 67°, and 45°). The simulation of microstructure development in specimens built along the Z-axis, applying all three scanning strategies, showed that the as-built microstructure is strongly textured and is influenced by the scanning strategy. The 45° scanning strategy induced the highest microstructural texture from all scanning strategies used. The monotonic tensile test results highlighted that the material exhibits significant anisotropic properties, depending on both the specimen orientation and the scanning strategy. Regardless of the scanning strategy used, the lowest mechanical performances of IN 625, in terms of strength values, were recorded for specimens built in the vertical position, as compared with all the other orientations.

Experimental Investigation on 3D Laser Forming of Metal Sheet

2004 ◽  
Vol 471-472 ◽  
pp. 568-572 ◽  
Author(s):  
Li Jun Yang ◽  
Yang Wang ◽  
M. Djendel ◽  
L.T. Qi
Keyword(s):  
Laser Scanning ◽  
Laser Energy ◽  
Processing Parameters ◽  
Experimental Results ◽  
Laser Source ◽  
Laser Forming ◽  
Scanning Strategy ◽  
Temporal And Spatial Distribution ◽  
Scanning Velocity ◽  
Scanning Strategies

In this article, the relations between the formed shapes and process parameters had been studied for 3D laser forming of sheet metals. The investigation was performed on Stainless 1Cr18Ni9Ti sheet using a Nd:YAG laser source. The scanning strategies were being investigated to potentially achieve a more uniform temporal and spatial distribution of the laser energy, possibly leading to reduced part distortion, by scanning the beam across the sheet surface with both continuous and segmented irradiation geometries. The experimental results revealed that the cross spider scanning strategy could form square and circle sheets into spherical domes. And the radial lines scanning strategy could form rectangle sheets into saddle shapes. It was also apparent from the experimental results that the height of the center of the formed sheet increased with the increasing of the laser power and scanning numbers. The height of the formed square sheet firstly decreased with the laser scanning velocity increasing and began to decrease at a certain processing parameters by cross spider strategy, in which the circle sheet was opposite with the square sheet, and in which the rectangle sheet decreased with speed increasing.

scholarly journals Powder Bed Selective Laser Processing of Alumina: Scanning Strategies Investigation

2022 ◽  
Vol 12 (2) ◽  
pp. 764
Author(s):  
Mohamed Abdelmoula ◽  
Gökhan Küçüktürk ◽  
Enrique Juste ◽  
Fabrice Petit
Keyword(s):  
Surface Roughness ◽  
Numerical Model ◽  
Relative Density ◽  
Process Parameters ◽  
Laser Processing ◽  
Scanning Speed ◽  
Scanning Strategy ◽  
Powder Bed ◽  
Scanning Strategies ◽  
Future Work

Powder Bed Selective Laser Processing (PBSLP) is a promising technique for the additive manufacturing of alumina. For the method’s success, PBSLP process parameters such as laser power, scanning speed, hatching distance, and scanning strategies need to be investigated. This paper focuses on studying the scanning strategies’ effects on the PBSLP of alumina numerically and experimentally. Scanning strategies such as linear with different orientation, concentric, and islands were investigated. A numerical model was developed in which the PBSLP parameters, scanning strategy effects, and interpreting the experimental results could be observed. The numerical model proved its ability to reach the proper process parameters instead of using experimental trails which are time and cost consuming. For relative density, the island strategy succeeded to print alumina samples with a high relative density reaching 87.8%. However, there are round passages formed inside the samples that remain a barrier for the island strategy to be effectively used in PBSLP of alumina. Both linear and concentric strategies achieved a relative density of 75% and 67%, respectively. Considering the top surface roughness, samples printed with linear strategies gave low top surface roughness compared to the island and concentric strategies. Linear-45° is considered the effective strategy among the studied strategies as it achieved good relative density and low roughness at top and side surfaces. For PBSLP of alumina, new scanning strategies should be considered, and this study presents a new scanning strategy that is mainly based on space filling mathematical curves and should be studied in future work.

Analytical Solution of Temperature Distribution in a Nonuniform Medium Due to a Moving Laser Beam and a Double Beam Scanning Strategy in the Selective Laser Melting Process

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Loong-Ee Loh ◽  
Jie Song ◽  
Fenglin Guo ◽  
Guijun Bi
Keyword(s):  
Temperature Distribution ◽  
Analytical Solution ◽  
Laser Beam ◽  
Selective Laser Melting ◽  
Melting Process ◽  
Laser Melting ◽  
Scanning Strategy ◽  
Beam Scanning ◽  
Double Beam ◽  
Scanning Strategies

Selective laser melting (SLM) has received increasing attention in recent years as an innovative manufacturing technique. The present SLM process only uses a single laser beam to melt and consolidate the powder, which may result in excessive evaporation. In this paper, a double beam scanning strategy is investigated in which the first laser beam preheats the powder just below the sintering point while the second laser beam completely melts the powder. An analytical solution on the temperature distribution heated by a moving laser beam in the powder-bulk domain is derived and is used to determine the critical radius of the first laser beam. The single and double beam scanning strategies are compared numerically and it is found that double beam scanning can effectively reduce material evaporation and increase the amount of powder melted in the SLM process.

scholarly journals Effect of Scanning Strategy in the L-PBF Process of 18Ni300 Maraging Steel

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 826
Author(s):  
Francesco Rivalta ◽  
Lorella Ceschini ◽  
Anders E. W. Jarfors ◽  
Roland Stolt
Keyword(s):  
Laser Powder Bed Fusion ◽  
Scanning Strategy ◽  
Powder Bed ◽  
Maraging Steels ◽  
Material Hardness ◽  
Final Microstructure ◽  
Quench Cracking ◽  
Scanning Strategies ◽  
Powder Type ◽  
Physical And Chemical

Maraging steels are good candidates for the laser powder bed fusion process (L-PBF), also known as Selective Laser Melting, due to excellent weldability and resistance to quench cracking. Powders physical and chemical characteristics dominate the final microstructure and properties of the printed parts, that are also heavily influenced by the process parameters. In this study, the effects of the scanning strategies on dimensions, average surface roughness, density and material hardness were evaluated, keeping the powder type and the volumetric energy density (Andrew number) constant. The effects of the scanning strategy on these properties are far less understood than on other important ones, like residual stresses and distortion, strongly affected by the scanning strategy. In this study, parallel stripes, chessboard and hexagonal pattern strategies were studied, keeping the Andrew number constant but varying the interlayer rotation. In general, the hexagonal strategy underperformed compared to the chessboard and the stripes ones.

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